Fiber optic communication has been hailed as the superior method of transmitting video, audio, data and various analog signals. Optical fibers offer many well known advantages over twisted pair and coaxial cable, including immunity to electrical interference and superior bandwidth. For these reasons, fiber optic transmission systems have been increasingly integrated into a wide range of applications across many industries.
While fiber optic transmission has dramatically improved the stability and accuracy of conventional copper based transmission mediums, fiber optic technology has continued to use the same, traditional, analog based signaling techniques. A new generation of products employing pure digital signaling to transmit analog information brings fiber optic transmission to a new, improved level.
Fiber optic transmission systems are sold in both amplitude modulation and frequency modulation versions. In both systems, an optical transmitter receives an analog data signal and converts it to an optical signal.
In existing amplitude modulation systems, various distortions occur to the transmitted signal. For example, there is a degradation in the signal to noise ratio as the length of the fiber optic cable is increased. Also, there are non-linear differential gain and phase errors of video signals and poor dynamic range of audio signals, etc.
In existing frequency modulation systems, the need to transmit electrical signals over fiber optic cables from sources in high electromagnetic fields or anechoic chambers to monitoring equipment in low field areas exist. Additionally, there is the need to reduce electromagnetic interference of the transmitted signal without compromising signal integrity.
Therefore, it is apparent that a need exists for techniques to eliminate the various distortions in amplitude modulation fiber optic transmission systems. Furthermore, it is apparent that a need exists within frequency modulation systems to be able to transmit electrical signals over fiber optic cables from sources in high electromagnetic fields or anechoic chambers to monitoring equipment in low field areas. Furthermore, in frequency modulation systems there is a need to reduce electromagnetic interference of the transmitted signal without compromising signal integrity.